Fractional extraction of mineral oils



Patented Jan. 13, 1931 UNITED STATES PATENT ol-"rics' LAN'I'IG DEFININGCOMPANY, OF PHILA OF PENNSYLVANIA p smmoun w. rams, on rnrnnnnnrnm,rmmsvnvmm, ASSIGNOB T0 man u- DELPHIA, rmmsxmmmn, a common-r10!\I'BACTIONAL nx'r'nacrron or MINERAL one No Draw1ng.. Application filedJuly 16,

My invention relates to the art of'mineral oilrefining, with particularreference to the separation of crude petroleum or petroleum productsinto fractions of different. chemical compositions 'while. ofapproximately the same distillation range.

' In accordance with my invention crude pein these and some of whichhave a chain.

structure and some a ring structure. A large number of individualhydrocarbons of each series are present and have different boilingpoints.

In the various typesof crude petroleumcommonly known as paraffin base,naphthenic or asphalt base, and mixed base these various series ofhydrocarbons are present in different proportions. For example, in theparafiin base crudes such as those from the Appalachian field there is arelatively high proportion of the hydrocarbons having a chain structureand a high hydrogen to carbon ra' tio, whereas in the so-callednaphthenic crudes there is a relatively high proportion of hydrocarbonsof the ring structures and lower hydrogen to carbon ratio. The mixedbase crudes such as those fromthe Mid Continent area are intermediatebetween these two extreme cases.

, .In the normal refining processes for crude petroleum, the fractionsof varying dlstllla- 'tion ranges which are successively obtained.tained upon the starting material before ex-- 1 in distillation of theoils partake of the general character of the crude; for example,Inbricating oils from A'ppalachian crudes will show parafliniccharacteristics whereas the oils from the naphthenic crudes shownaphthenic characteristics. The physical properties of the resultantoils are dependent in thls 1927. Serial no, 206,388.

way upon the chemical composition of the crude oils from which they arederived. For the same distillation range, a paraflinic oil will show alower viscosity, a lower specific gravity, and a lower refractive indexthan a na hthenic oil.

imilarly a paraflinic oil of 9; given viscos ity will show a lowerspecific gravity and re-.

ity. The position of this curve is typical of I i the crude and of theoils which maybe pro duced from it by processes heretofore wellknown.For example, an oil of 80 seconds Saybolt universal viscosity at 210 F.from a certain Pennsylvania crude has a specific gravity of 0.885whereas an oil of the same VISCOSltY from a typical .Gulf Coast crudehas a specific gravity of 0.943. These relationships are fully discussedin Hill and Ferris, Industrial and Engineering Chemistry, vol. 17 page1250 (1925).

Ience, if a fraction obtained .by distillation, for example fromaMid-Continent crude, be subjected to-an extraction and separation inaccordance with my invention hereinafter set forth more in detail, theextract resulting, upon separation into a number of fractions bydistillation, and upon determination of'the specific gravities andviscosities of said fractions and plotting said speeific gravities asordinates and said viscosities asabscissae and drawing a curve throughthe points so plotted, the extract will be characterized by said curve.Furthermore, such curve will be found to lie definitely above a curvesimilarly plotted 'for similar data obtraction, that is to say, afraction of the extract having agiven viscosity will have a greater secific gravity than the specific gravity 0 a fraction of thestartingmaterial of the same viscosity; and in accordance with the terminologyused herein and in .the ap pended claims, such extract is referred to asone richer in naphthenic hydrocarbons or compounds. The undissolvedfraction, or that fraction remaining after extraction and separation asaforesaid, may also be represented by a curve plotted from similarlyobtained data, which curve will fall definitely below the curvecharacteristic of the starting material before extraction; and inaccordance with the terminology of this a plication and of the appendedclaims such raction is referred to as one richer in paraflinichydrocarbons or compounds.

When the properties characteristic of naphthenic oils were desired,heretofore it has been necessary to obtain such oils from a naphtheniccrude, whereas on the other hand where paraffinic properties weredesired,-it has been necessary to start with a paraifinic crude. .Onaccount of certain qualities of the oils produced, the paraflinic crudeshave long been at a premium since even with a mixed base crude ofrelatively high parafiinic characteristics the oils produced have beensomewhat more na hthenic than those from the strai ht para n base crudesand have, therefore, een less desirable for certain purposes.

'I have found that oils containing both the paraflinic series ofhydrocarbons and the various naphthenic series maybe fractionallyextracted with a suitable solvent such as a rious series of hydrocarbonspossess a differential solubility in this solvent, the na htheniccompounds being much more solu le,

than the paraflinic hydrocarbons. By means of extraction withnitrobenzene, it is, therefore, possible to elfect a partial separationof the naphthenic compounds from the paraflinic and to obtain from anoil containing both classes an oil which is much more paraf- 1 finicthan the'original and one which is much fnore naphthenic. By myinvention, for example, it is possible to produce an oil of the qualitynormally obtained from Appalachian crudes from crudes of the mixed basetype from the Mid Continent area and, conversely, to obtain oils frommixed base crudes such are normally obtained from the naphthenic oilsfrom the Gulf Coast area.

In practicing my invention, I prefer to mix the oil fraction to betreated with a suitable proportion of nitrobenzene at elevatedtemperatures so that complete solution is offected and a'homogeneousliquid obtained.

Ithen cool the mixture and produce a separation into two layers, theupper one of which is a solution of nitrobenzene in the more paraflinicportion of the oil and the lower layer of which-is a solution of themore naphthenic portion of the oil in nitrobenzene. Instead of thisheating and cooling I may also simply agitate the cold mixture. Wherelarge quantities, of solid hydrocarbons are present which may belong tothe true paraiiin series CHI-1 m, these solids or waxes remain in theupper layer and may cause it to be solid or seml-solid. I then effectseparationof. the two layers by decantation or other means and removethe nitrobenzene from each of the separated oil layers by distillationor other means, obtaining thereby two oils of similar distlllationranges but of widely different physlcal characteristics andcorrespondingly dlflerent chemical compositions.

Before removing the nitrobenzene from the upper layer obtained in theabove described process, I may add a further quantity of nitrobenzeneand repeat the process for an extractlon of further naphthenic bodiesfrom the 011. The extraction may be so repeated two or three times, wasoften as desired. In wax-bearing oils, the finally extracted product soobtained is a mixture of solid and liquid hydrocarbons. While the exactchemical compositions of these compounds are not known, it is probablythe fact that the llqllld hydrocarbons are branched chain hydrocarbonsof the paraffin series Whereas the solid bodies are straight chainparafiln hydrocarbons. This product may be further separated intosolid'and liquid hydrocarbons by any of the well-known dewaxingprocesses,

such as the cold settling process in which the 011 is diluted withnaphtha, chilled, the solid hydrocarbons allowed to settle, the clearsupernatant liquid decanted oil", and the naphtha removed from bothportions by distillation.

As an example of my process, there is descr bed below the treatment ofa'high viscosrty wax-bearing distillate obtained from a typical Texasmixed base crude with the product-ion of oil fractions of a naphtheniccharacter, an oil fractionof a parafiinic character, and a solid wax. Toan oil of the aforesaid source havlng a viscosity of 90 seconds Sayboltuniversal at 210 F. and a specific gravity of .9156-at 15 C., I may adda quantity of nitrobenzene in the proportion of about two gallons pergallon of oil. The mixture is heated to about 60 C. and agitated untilsolution is effected. The oil is then cooled with gentle agitation toabout 10 C.

obtained are shown in the table below I Specific Vis. Bays}? gravitybolt univ. 3 2 @g r. (actual) a 0 al 011 89.8 0.9168 Dls ii l ved oillrom extraction #1.-." 148. 2 0. 9603 0.920 Dissolved oil fromextraction #2.-." 96. 4 0. 9252 0. 916 Dissolved oil from extraction#3... 74. 0 0. 8997 0. 911 Undissolvcdoil (dewaxed) 69. 0 0. 8707 0. 910

A different chemical composition of the fractions is shown by thedifierence between the actual specific gravities and the calculatedspecific gravities of the, oils produced by these extractions. Thislatter column indioates the specific gravity corresponding to. theviscosity if the oil had been obt ned from the crude from which the origna 011 was produced, by normal distillation and refining processes.Thus, on extracted fraction #1, which is the oilobtained from thenitrobenzene'layer from the first extraction, a the actual specificgravity is much higher than the calculated, indicating that the fractionis much more naphthenic than would normally be'produced -from this typeof crude. On the other, hand, in the case of the residual oil which isthe oil port on obtained after the cold settling of the finallyextracted product, the actual specific gravity is much lower than thecalculated, showing that the oil is much more paraflinic than theoriginal. The wax obtained 18 the high melting product such as would beobtained from such an original oil by any of the wellknown processes ofwax removal- It will be noted that the oils obtained by the second andthird extractions possess properties between the two extremes, i; e. theresidue from extraction- #2 hasan actual specific gravity somewhathigher than the theoretical specific gravity, indicating a morenaphthenic oil than ordinary distillation and refining processes wouldyield, while in the case of the residue from extraction #3, the actualspecific gravity is lessthan the calculated value showing the oil to bemore para'llinic.

That this process is one of separation into classes rather than one ofchemical reaction between the oil and the nitrobenzene is shown by thefact that upon mixing the various oilv fractions and the wax in theproportions n which they were obtained from the original oil, theresultant product is the same astheoriginal oil, as indicated by thephysical p p w f While I have described m' process with the use ofnitrobenzene as the so vent, I do not intend to limit myself to thisparticular compound but ma mono-nitro-nap thalene-or' other suitablenitro derivatives of an aromatic h drocarbon.

It will be seen that by the use 0 myprocess I am practicall inde nden't'of the particuse instead nitrotoluene,

ular nature of t e cru e sources but may produce viscous oils of anyrequired characteristics from practically any source.

For example, I am able, by my (process, to produce from petroleum of amixe base type such as would, on normal batch distillation, give aresiduum of a viscosity of 150 seconds aybolt universal at 210 F. with aspecific gravity of .928 or more, a lubricatin stock with a viscosity of150seconds Say It or.

more and a specific gravity not higher than .910. This lattercombination of properties is typical of'cylinder stocks produced fromPennsylvania crude. V l

I find in many ins'tances'that the oils produced by my process aresuperior to those produced under the most favorable conditions by normalprocesses from selected crudes.- I

' For example, it is well-known that oils containing appreciablequantities of paraffinic constituents decomposeunder the action of theelectric corona with the formation of an amorphous solid material,commonly known as corona wax. This property is highly detrimental inoilsfor electrical insulating purposes. It is diflicult, by normalprocesses, even from carefully selected crudes to obtain anoil'sufliciently low in paraflinic constituents to satisfactorilywithstand the action of the corona. By my process, it isreadily possibleto produce such'an oil as the nitrobenzene extract which will show noformation of coronawax on exposure to corona mally made.

herein for treatment in accordance with my process are those having asubstantial viscosity, and are herein described as viscous when having aviscosity of '50 seconds Saybolt universal at 100 F., and upward.

For brevity in the appended claims the ,termnitrobenzene is employed ina ge- The mineral oils particularly contemplated neric sense to includethat material and equivalent aromatic n tro compounds or mixtures ofthem.

By fractional extraction in the appended claims- I mean the process ofcontacting the material to be extracted with one or'more portions of asolvent and separating the solvent and soluble portion from the nsolubleportion after each contacting.

ieo

- theories.

Herein, while I have discussed the theories which I believe underlie myinvention, it is to be understood that I do not intend to be heldthereto, and that my invention Concerns actual physical phenomena, andis in no way predicated upon the correctness of said Furthermore, it isto be understood that the results attained by my process do not dependupon the presence in the oil to be treated of paraflins, solid atordinary temper. tures, commonly known as wax. If present, such parafinsmay be removed either before the oil is subjected to my process, or ifdesired, from the fraction or fractions containing them attcr suchtreatment, as for example, by the well-known cold settling process. Ifthe latter procedure is resorted to, the substantially dewaxed extractwill be found to be richer in 'naphthenic hydrocarbons or compounds thanthe similarly-dewaxed original oil with out extract-ion, while thedewaxed undissolvcd oil will be found to be richer in paraffinichydrocarbons or compounds than said dewaxed original oil. It willtherefore be seen that my process is adapted to the treatment ofwax-free oils as well as wax-containing oils. v

What I claim is: 4 I

- 1. In the art of refining mineral oils the process which comprisesbringing a viscous oil containing paraflin and naphthenic hydro: carbonsinto contact with nitrobenzene, thereby effecting solution of a portionof the oil richer in naphthenic hydrocarbons in the nitrobenzene,separating the nitrobenzene solution of oil 'from the oil so treated,and removing. the nitrobenzene from each of the fractions so obtained.

2. The process of separating mineral oils into fractions .whichcomprises'bringing a viscous oil containing paraflin and naphthenichydrocarbons into contact with nitrobenzene thereby effecting solutionof a portion of the oil richer in naphthenic hydrocarbons in thenitrobenzene, separating the nitrobenzene solution of oil from the oilso treated, and distilling the nitrobenzene from each of the fractionsso obtained.

temperature as to effect solution, cooling the solution to form a. twolayer system, and sepmsaaee f arating the upper layer from the lowerlayer.

-5. In the artof refining mineral oils the process which comprisesadding nitrobenzene to a viscous oil containing parafiinic andnaphthenic hydrocarbons, heating the mixture to such a temperature as toeffect solution, cooling the solution to form a; two layer system,removing the lowerlayer, and similarly retreating the upper layer withnitrobenzene.

6. The method of producing parafiinic lubricating oilfrom mixed basecrude which comprises distilling the crude and bringing a portionthereof into contact with nitrobem zene, thereby partially dissolvingthe oil, separating the nitrobenzene, solution of oil from the oil sotreated, and removing the nitrobenzene from the treated oil.

7. The process of producing a lubricating stock of specific gravity-lessthan .910 and of Saybolt universal viscosity greater than 150 seconds at210 F. from a crude petroleum which on normal distillation yields aresiduum of 150 seconds viscosity at 210 F. and a specific gravitygreater than .928, which coinprises producing a residuum from the crudepetroleum, and extracting said residuum from said crude petroleum withnitrobenzeno. 8.: In the art of refining mlneral oils, thc

process which comprises separating a viscous oil containing paraffinicand naphthcnic hy drocarbons into fractions respectively richer inparaifinic and naphthenic compounds by extracting said oil withnitrobenzene.

9. In the art of refining mineral oils. the process which comprisesfractionally extracting aviscous oil containing parafiinic andnaphthenic hydrocarbons with nitrobenzene to produce fractions of theoil respectively richer in paratfinic and naphthenic compounds. a i

10. In the art of refining mineral lubricating oil containing paraflinicand naphthenic hydrocarbons, the step of fractionally extractin g theoil with nitrobenzene, to effect a separation of fractions respectivelyricher in paratfinic and naththenic compounds.

11. The process of producing a lubricating stock of specific gravityless than .910 and ot' Saybolt universal viscosity greater than 150seconds at 210 F. from a crude petroleum which on normal distillationyields a residuum of 150 seconds viscosity at 210 F. and a specificgravity greater'than .928, which comprises separating a residuum fromsaid crude petroleum and bringing such residuum into contact withnitrobenzene, to effect solution of a portion thereof with nitrobenzene.separating the nitroben-zene solution of oil from the portion which doesnot dissolve therein, and removing the nit-robenzenc from the oil ofsaid solution. 7

12. In a process for separating a viscous mineral oil containingparaffinic and naphthenic hydrocarbons into fractions which arerespectively richer in naphthenic hydrocar amuse honsfand parafiinichydrocarbonsother than u wax, the step which comprises extracting theoil'with nitrobenzene. s f 13. .In aprocess for separating viscousmineral oil liquid at ordinary temperature containingparafiinicand-naphthenic hydro carbons into fractions respectivelyricher in paraflinic 1 and naphthenic hydrocarbons, the v a p whichcomprises extracting the oil with nitroben'zene.

14. 1 In a process for separating a substan- 'tially wax free viscousmineral oil containing parafiinic and naphthenic hydrocarbons intofractions respectively richer inparafiinicand i naphthenic hydrocarbons,the step'which comprises extracting the oil with nitrobenzene. 15. Theprocess of treating a viscous frac- T tion of a crude oilof one typecontaining go paraflinic and naphthenic-hydrocarbons to procure afraction having the quality of a corresponding fraction of a crude oilof different type having a greater content of paraffinic hydrocarbons,which comprises extract- '25 in the viscous fraction with nitrobenzene,

and separating the oil so treated into portions respectively richer inparaifinic and naphthenic hydrocarbons, 16. The process of treating aviscous frac- 80 tion of a-mixed base crude oil to procure a fractionhaving the quality of a correspond- 4 ing fraction of a parafiinic basecrude. which comprises extracting the viscous fraction withnitrobenzene, and separating the oil so 3 treated into portionsrespectively richer in paraflinic and naphthenic compounds.

17 In the art of refininn mineral oils, the process which comprisesaddingnitrobenzene to a viscous oil liquid at ordinary tempera- 40.tures containing parafiinic and naphthenic Q hydrocarbons. heating themixture to a temerature sufiicient to effect solution. cooling thesolution to a temperature suflicient to form two layers respectivelyricher in naph- '45 thenic hvdrocarbons and paraflinic hydrocarbonsother than wax, and se arating the upper'laver richer in paraflinichydrocarbons from the lower layer richer in'naphthenic hydrocarbons. 18.In the art of refining mineral oils. the rocess which comprisesaddine'nitrobenzene to a viscous oil liquid t ordinary temperaturescontaining paraflinic and naphthenic hydrocarbons. heating the mixtureto'a temerature sufiicient to eflect solutiom cooling the solution to atem erature sufiicient to form two layers. se arating nitrobenzene andparafiin wax from the upper laver.'-and sepa-' rating nitrohenzene fromthe lower laver to .60 produce one fraction richer in parafiinic and asecond fraction richer in n aphthenic hydrocarbons than said vi scnusoil;

SEYMOUR w. FERRISI.

M QERT'IFIGA'I'E 0F coRREcTIdN. e v Patent 1(0. 1, 788,569. I January15f, l93.1,

. SEYHOUR'YW. FERRIS. e

it hereby. certified izhat error appears in the printed apeciticm'zien Aof the afbove numbered patent requiring correetien eel-follows: Ifege L,i1nes 32 end-b2, "claims 1 and 2 respectively, for the word '"bareffin'read par -affinic; and that the said. Letters Patent should be read withthis eer;-

rection' therein that the same nay'cenfonn' totherecbrd of the eerie inthe" Patent Office.

Signed and sealed-this Z'jthfiay' 9f January, "A D. 1938.

v w Henry Van Arsda leg (Seal) Acting Commissioner of Patents.-

